Previous rotary lawnmower blades generally comprise a simple rectangular strip of metal provided with cutting edges by an angular surface ground on the top of the blade and achieving lift by means of a simple curled surface at the back edge of the blade. While such blades function adequately when large amounts of power are readily available, it has been found that these blades are not, in fact, capable of really good performance in terms of either cutting, vacuuming or bagging without excessive amounts of energy being wasted. Other blade designs exist for accomplishing other purposes but no prior art is known which in any suggests a blade configuration which is capable of good performance both as to cutting and as to developing a proper air flow.